CHICAGO — The Chicago Cubs won unanimous approval Thursday from the city's landmarks commission for their proposed $575 million renovation of century-old Wrigley Field, bolstering the team's plan to give a major facelift to one of the cathedrals of American sports.

The Cubs' controversial proposal includes adding two video scoreboards and five outfield advertising signs to the ballpark, which has drawn big crowds over the last 30 years despite the Cubs' long-established track record for losing.

Team owner Tom Ricketts, who hasn't had a winning season since buying the ball club in 2009, has contended that modernization and added revenue from advertising is badly needed to make the Cubs competitive as they slog through a season that has them on pace to lose more than 90 games for the fourth straight year.

Owners of neighboring businesses that owe their livelihoods to rooftop seating that allows their customers to see the action at Wrigley have fought the plan, saying it will put them out of business by blocking their views. The only potential remaining roadblock to the project: litigation from the rooftop owners.

Several city residents and business owners told the commission Thursday that the Cubs' plan would do irreparable harm to one of the city's treasures and the neighborhood around the park.

The Cubs got some backing from the public at Thursday's meeting. One self-described longtime "bleacher bum" said Ricketts needs the revenue if he is ever going to put together a winning team. "Remember, we're waiting for a World Series," said Trudie Acheatel, 68, of Chicago. "I'd like to see it in my lifetime."

The neighboring rooftop owners could still sue to block the project.

The Cubs decided to push forward with their ambitious plan after declaring they were at an impasse with the rooftop owners when the team first floated them a year ago.

The Cubs' plan also calls for tripling the size of the players' clubhouses — considered the worst in baseball — adding lights and relocating bullpens from foul territory to a spot under the bleachers.

GALLERY: HOME OF THE CUBS

Buy Photo

Wrigley Field turns 100 years old April 23. It's one of the oldest active major league parks -- second to Fenway Park. Dennis Wierzbicki, USA TODAY Sports

Like this topic? You may also like these photo galleries:

The Cubs last year offered to scale back their plans to two signs if the 15 rooftop owners — who have an agreement that goes into 2023 to share 17% of their gross revenue from game day parties they host when the Cubs are playing — agreed not to sue.

Unable to hatch a deal, Ricketts announced in May that the team, which has seen attendance slip each year since he bought the club, couldn't afford to wait any longer and would push its more ambitious plan. Attendance was at 3.16 million in 2009, dropped to 2.6 million last season and is on pace to drop again in 2014.

Last week, some rooftop owners signaled they'd be willing to accept the scaled back plan of two signs, but the Cubs have indicated they intend to move forward with the more ambitious plan that adds four LED signs of up 650 square feet and a 2,400 square foot video board in right field.

"The plan approved today for Wrigley Field is a step forward for the Cubs and the neighborhood," Chicago Mayor Rahm Emanuel said. "Not only does it upholds the architectural heritage of the stadium that Chicagoans can enjoy, but it will generate thousands of jobs. I fully expect the owners to initiate the restoration of Wrigley Field and to invest in the surrounding Wrigleyville area, including traffic flow, security, and public parks. In addition, discussions with the rooftop owners should - and must - continue so that this plan remains a win-win."

Emanuel earlier this week suggested the Cubs find a resolution with the rooftop owners and pay attention to concerns from residents in the neighborhood who have raised concerns about the rehab project, which also calls for building a 175-room hotel, an open-air plaza and office building adjacent to the park.

Chicago Cubs fans use neighboring rooftops to watch games, but they might no longer have unobstructed views. A proposed renovation of Wrigley Field includes placing signs and video boards that could block the views.